Process for the improvement of the storage properties of urea



United States Patent 3 299 133 PROCESSFOR THEdMiROVEMENT OF THE STORAGE PROPERTIES OF UREA Ernst Peterhans, Visp, and Friedrich Schiltknecht, Post- 3,299,133 Patented Jan. 17, 1967 ment. It may prove advisable, in this instance, to reheat the material following the application.

It is also possible to add the amide to an aqueous urea solution in the course of the synthesis of urea, or to a urea gaclz, Bi'aseli, Switzerland, assignsors to Eonza Ltd., Base], 5 melt which had already been dehydrated and contains an a (fol'lmlfifioll 0 Witlel and onl a few ercents of water recedin or durin the No Drawing. Filed Oct. 20 1964, Ser. No. 405,243 y p p g Claims riority a licati s t er] nd 0 t 24 1953 granulaton process p pp 5 7 a c The result in any of these treatments will be a urea 11 (CL 260 555) which is characterized by good storability and remains free-flowing.

15 known that "urea 18 y p even When The additives conforming to the invention are applied Pulled 550mb a Tesult, l granules Urea tend P in quantities of less than 1 percent, preferably in amounts 1156 f k l storagelcallslng the Sub-Stance to 105% Its of 0.05-0.8 percent by weight relative to the urea.

ree- OWlng c aracterlstics.

The practice of improving the storability of urea 15 EMMPLES through the addition of inorganic substances, such as e.g. (l) 4 kgs. of urea granules are thoroughly mixed in a double salts, for instance, aluminum ammonium sulfate blender with formamide, acetamide, propionamide or a or diatomaceo-us earth, is known from the literature. It mixture of formamide and acetamide, in the amounts is further known that it is possible to improve the storshown in Table 1. Some of the material was reheated ability through surface treatment with adduct'forming sub- 20 after the blending. The urea specimens thus treated were stances, eg. the higher fatty acids, their derivatives or then pressed for 4 days in 4 kg. bags under a pressure the higher hydrocarbons. All of these known methods of 2 tons. are suitable if the urea is to be used as a fertilizer. If, The results are presented in Table 1. The lumpiness, however, the urea is to serve as the raw material for the given in weight percents of urea, indicates the amount of production of plastics, such substances constitute a harmurea remaining in the form of. lumps after a single drop ful interference. from a height of 15 cm.

Table 1 Amount Water Heating, Duration of Lumps, Additive Weight Addition, C. Heating, hrs. percent percent percent s2 0. 05 0.5 35 0.1 2 0. 25 0.5 0. 25 2 22 0.05 2 4 0.1 2 2.5 0. 25 2 0.0 0. 25 0.25 2 0 0. 25 0.25 0.6 0.05 0. 05 95 2 12 0.1 0.1 95 2 8 0. 25 0.25 95 2 9 0.1 82 0.5 13.4 Acetamide 1:1 0. 25 82 0. 5 0

Another group of known methods involves the use of additives which do not interfere with the utilization of urea as a raw material for the plastics industry. These additives consist mostly of watersoluble 'gly-oxal-formaldehyde and urea-formaldehyde condensation products, which must be specially prepared accordingly to suitable methods.

It has now been discovered that it is possible to improve the st-orability of granular urea in a simple manner through the addition of amides of lower carboxylic acids.

An object of the invention is the improvement of the storage characteristics of urea through the addition of stora-bility-improvin-g additives, characterized by the fact that the said ,storability-improving additives consist of amides of the lower carboxylic acids having a carbon chain consisting of l to 4 carbons, said amides to be used in amounts of less than 1 percent by weight relative to the urea.

The amides of the lower carboxylic acids can be applied either in the pure form or as aqueous solutions. They can also be used in the form of mixtures. The use of acetamide is preferred.

The amides can be added to the urea in a great variety of ways. It is thus possible, for example, to apply an amide to the already prille d urea through a surface treat- (2) Mixtures of acetamide and water in a 1:1 proportion were added with the aid of a proportioning pump to a meat melt to be prilled and containing less than 1 percent of water; the mixture was then prilled. Table 2 presents the results obtained with varying amounts of the acetamide additive. The urea was thenas described in Example 1-pressed for 4 days under a pressure of 2 tons.

Table 2 Acetamide weight, percent Lumps, percent 0 0.18 27 0.33 11 0.6 2. 1.0 27

When 0.5 percent by weight of acetamide was used, the lump formation amounted only to 3-4 percent.

We claim:

1. The process for improving the storage characteristics of urea which comprises incorporating therewith an effective amount up to less than about one percent by weight thereof, of an amide of a lower carboxylic acid containing from 1 to 4 carbon atoms per molecule.

2. The process defined by claim 1 wherein a mixture of said amides is so incorporated.

3. The process defined by claim 1 wherein the amide is aceta-mide.

4. The process defined lby claim 1 wherein the amide is incorporated in an amount from about 0.05 to about 0.8 percent by weight of the urea.

5. The process defined by claim 1 wherein the amide is applied to the surface of urea.

6. The process defined by claim 1 wherein the amide is incorporated into an aqueous urea solution.

7. The process defined by claim 1 wherein the amide 4 is incorporated with a urea melt of low water content as the urea is prilled.

8. A storage-stable urea containing a small and efiective amount to improve the storage characteristics thereof up to less than one per-cent by weight thereof, of an amide of a lower carboxylic acid containing from 1 to 4 carbon atoms per molecule.

9. A storage-stable urea defined by claim 8 containing from about 0.05 to about 0.8 percent by weight of said amide.

10. A storage-stable urea defined by claim 8 containing a mixture of said amides.

11. A storage-stable urea defined by claim 8 wherein the amide is acetamide.

No references cited.

ALEX MAZEL, Primary Examiner.

20 HENRY R. JILES, Examiner. 

1. THE PROCESS FOR IMPROVING THE STORAGE CHARACTERISTICS OF UREA WHICH COMPRISES INCORPORATING THEREWITH AN EFFECTIVE AMOUNT UP TO LESS THAN ABOUT ONE PERCENT BY WEIGHT THEREOF, OF AN AMIDE OF A LOWER CARBOXYLIC ACID CONTAINING FROM 1 TO 4 CARBON ATOMS PER MOLECULE. 